Track maintenance apparatus



Oct. 15, 1963 Filed March 19, 1959 ig. I

D. J. HOGAN EI'AL TRACK MAINTENANCE APPARATUS LILJHI-l 5 Sheets-Sheet 1IN VEN TORS. "Q Donald J Hogan y Warren J. Smith Merriam, Larch 8 SmithA7 TOR/VEYS Oct. 15, 1963 D. J. HOGAN EIAL 3,107,168

TRACK MAINTENANCE APPARATUS Filed March 19, 1959 5 Sheets-Sheet 2 um Qkmm t wm t Oct. 15, 1963 I D. J. HOGAN ETAL 3,107,168

TRACK MAINTENANCE APPARATUS Filed March 19, 1959 5 Sheets-Sheet 5 Fig. 5

INV EN TORS Dana/d d Hogan BY Warren J. Smith Merriam, Larch 8 Sin/fl;

ATTORNEYS Oct. 15, 1963 D. J. HOGAN ETAL 3,107,168

TRACK MAINTENANCE APPARATUS Filed March 19, 1959 5 Sheets-Sheet 4JNVENTORS. Dona/a J. Hogan y Warren J. Smif/r Merriam, Lara/7 8 Smith ATTOR/VEYS United States Patent 3,107,168 TRACK MAINTENANCE APPARATUSDonald J. Hogan, Chicago, and Warren J. Smith, Glen Ellyn, Ill.; saidSmith assignor, by mesne assignments,

to Donald J. Hogan, doing business as Donald J. Hogan 8; Company,Chicago, Ill., a sole roprietorship Filed Mar. 19, 1959, Ser. No.800,600 6 Claims. (Cl. 8814) This invention rel-ates to maintenanceequipment for railroad track installations. It is more specificallydirected to railroad track aligning apparatus.

Although considerable care is employed in preparing the bed for railroadtrack installations, the constant impact of high speed rolling equipmenton curved and tangent track structure results in a misalignment of theoriginal track profile. Track maintenance equipment is available forlaterally adjusting or raising track structures in order to correct anymisalignment and provide kink-free and level surface track. The instantinvention is concerned with auxiliary apparatus for use in cooperationwith track aligning equipment to provide a datum line for the aligningoperation.

In the drawings,

FIGURE 1 is a schematic side view showing the relative position of thecomponents of this invention.

FIGURE 2 is a schematic plan view of the illustration in FIGURE 1.

FIGURE 3 is a plan view of a preferred embodiment of the opticalsighting component.

FIGURE 4 is a side elevation of a mounting arrangement for the opticalsighting component.

FIGURE 5 is a side view of the optical sighting component mount shown inFIGURE 4.

FIGURE 6 is a schematic view of the optical system employed in thesighting component shown in FIGURE 3.

FIGURE 7 shows the prism stool utilized in mounting the coincidenceprism in the optical sighting component shown in FIGURE 3.

FIGURE 8 is a side elevation view of one embodiment of the forwardtarget station.

FIGURE 9 is a side view of the embodiment of the forward target stationshown in FIGURE 8.

FIGURE 10 is a side elevation view of one embodiment of the rear targetstation.

FIGURE 11 is a side view of the rear target station shown in FIGURE 10.

FIGURE 12 is an elevation view of one embodiment of the intermediateobservation station.

FIGURE 13 is a side view of the intermediate observation station shownin FIGURE 12.

FIGURES 14-17 are schematic illustrations of optical systems which canbe utilized in assembling the optical sighting component.

The apparatus of this invention has broad application in track aligningoperations; however, to facilitate a description of the invention thefollowing discussion will be directed to its use in track surfacing.This maintenance procedure functions to provide a level tr-ackstructure. From a previous inspection of a given stretch of misalignedtrack the amount that the track structure is to be lifted ispredetermined. Generally the raise will be about 1-6 inches. Maintenanceoperations are then carried out using one of the tracks as the gradetrack. A preliminary raise is effected by a conventional jack tie tamperwhich raises the track tothe established reference line and tamps theballast under the so-called jack tie at the raise to hold the track atthe desired elevation. This operation is carried out with the jack tielocated at rail joints, centers, and quarters, or other desired trackpositions depending upon the selected procedure. Immediately followingthis operation a gang tamper tamps the ballast under every tie to assurea uniform tamping of the ballast for the entire track structure.

The instant invention provides a-datum by employing an optical sightingdevice located at the jack tie tamper which is used to sight along atheoretical datum established by a pair of lineal targets locatedrespectively in front of and behind the jack tie tamper unit. Thesighting device is in contact with the track being raised and is sodesigned to sight along the datum and permit the operator of the jacktamper to determine when the desired raise has been made.

From the drawings, which show a complete specific embodiment of theinstant invention, it is seen that the track aligning apparatus of thisinvention is preferably employed in conjunction with a self-propelledpower unit 10 which is generally a so-called jack tie tamper such as theunit marketed under the mark Handyman by the Kalamazoo Mfg. Co. Powerunit 10 is fitted with flanged wheels 11 which engage with railroadtrack structure 12. Rear target station 13 is coupled to power unit 10by coupling means 14. Forward target station 15 is coupled to power unit10 in a similar manner by coupling means 16 but is spaced at a greaterdistance as will hereinafter be explained. Because of the length ofcoupler required for attaching forward target station 14, wheeledsupports can be used at spaced intervals along forward coupler 16 tosupport the coupler means or other coupling means employed to maintainthe desired spacing.

Mounted on each target station is a target board 20. The target boardcomprises a back board 21 which is traversed by a lineal target 22approximately wide seen in FIGURES 8 and 9. The area of back board 21 ispreferably as large as the area of the field of the telescopic elementsof hereinafter described optical sighting device at target distance. Inthe illustrated embodiment at target area about 5 feet square is used.Back board 21 is attached to the carriages preferably by means oftelescoping standards which are vertically adjustable and are held inposition by suitable stops. The target board on each target station ispositioned astraddle the grade rail and extends equally on each side ofthe rail. Automatic levelling devices, such as pendulums, can be used inmounting the target boards on the target stations to insure that thelineal target always assumes a horizontal position in track surfacinguse.

Forward target station 15 in the embodiment illustrated in FIGURE 8 hasa wheel base of about one-half of a standard length of railroad track,i.e. 20 feet. This minimizes deviations in the horizontal positioning ofthe lineal target 22. Carriage 23 is a light weight I-shaped structuralshape preferably made from aluminum and assembled from convenientlyhandled lengths. Yokes 24 are secured to the lower flange of the beamand serve as wheel mountings for holding the four double flanged wheels25 upon which carriage 23 rides. A pair of outriggers 26 extend fromcarriage 23 to provide stability to the station. Socket 27 is mounted onthe upper face of the beam and securely braced. Telescoping withinsocket 27 is adjustable upright 28 to which back board 21 is secured. Aplurality of pin and hole fasteners 29 is employed for incrementallyadjusting the height of lineal target 22. Adequate bracing is used toinsure the rigidity and stability of the target station.

Rear target station 13 shown in FIGURES 10 and 11 employs a rectangularcarriage 30 fabricated from C- channels. A pair of axles 31 areunderslung on carriage 30 and held in position by suitable journals.Flanged wheels 32 are mounted on axles 31 to provide a mobile unit whichcan be readily towed. Intermediate transverse frame member 33 supportsmounting 34 for the pivotally mounted back board 21. Telescopingstanchion is fastened at one end to mounting 34 and at the other end toa suitable mounting (not shown) on back board 21. Telescoping upright 36is used to support back board 21 at the desired height. Suitable bracing37 is also provided. With this arrangement the back board can be swungto either side of carriage 30 in the event that the grade rail ischanged by providing duplicate mounting brackets 38 on each side memberof the frame.

The intermediate observation station 39 illustrated in FIGURES 12 and 13employs a rectangular carriage 40 assembled from C-channels havingunderslung wheels 41 suitably mounted on axles secured to the carriageframe. Outwardly depending from side member 42 of the carriage frame isplatform 43 which is positioned vertically above the line track. Astanchion 44 is secured to platform 43 and extends upwardly to theobservation station located at a convenient level on power unit 10.Mounted atop stanchion 44 is cradle 45 employed for holding the opticalsighting device.

Cradle 45 as shown in FIGURES 4 and 5 comprises a frame 46 having sidemembers 47 and 48 which are joined to lower base 49. Stanchion 4-4extends through an opening 50 in lower base 49 and connects with amounting socket 51 secured to the under side of upper base 52 from whichcradle 45 is suspended. Upper base 52 fits within side members 47 and 48and is connected to the cradle assembly solely by leaf hinge 5-; whichcomprises a strip of thin spring steel 55 attached to the ends of theupper and lower bases 52 and 49 by mounting bars 55 which are traversedby threaded fasteners which engage with the base ends. Transverse saddleelements 56 and 57 are fastened to the frame sides which are alsoprovided with saddle cut-outs conforming to the portion of the sightingdevice resting therein. Hinged locking straps 58 and 59 and lockingscrews 60 and 61 cooperate with saddle elements to hold the sightingdevice in position.

Adjustable blocks 62 and 63, raised and lowered by thumbscrews 64 and 65which are threaded through brackets 66 and 67 fastened to the framesides, are employed to pivotally adjust the sighting device. Suitablepins 68 and 69 cooperating with blocks 62 and 63 and brackets 66 and 67are used to guide the vertical movement of the blocks. The angulardisplacement of cradle 46 and the sighting device mounted thereon withreference to stationary upper base 52 is controlled by adjusting screw'70. The shank of screw 70 penetrates lower base 49 through a suitableopening and threadably engages with upper base 52. In this position theunderside of lower base 49 rests on the shoulder portion of screw 70.

Optical sighting device which is mounted in cradle 46 on theintermediate observation station is a double objective optical systemwith the respective objectives contrarily facing and cooperating with anintermediate reflecting coincidence means and a suitable viewingobjective to permit simultaneous viewing of a pair of lineal targetspositioned each to the other at an angle of 180 in coincidence andrelative to a reticle. The illustrated viewing device 75 has a lenssystem schematically shown in FIGURE 6 and assembled as illustrated inFIGURE 3.

Objective 76 is a telephoto lens having a doublet lens 77 positive inpower and a single negative lens 78. The spaced components are mountedin tube 79 by conventional expedients. The other objective 80 consistsof a pair of spaced positive doublet lens 81 and 82 mounted in tube 83.Objectives 76 and 80 employ lens mountings for adjusting focal length.External threads on tubes 79 and 83 engage with internally threadedopenings 84 and 85 provided in prism housing 86 to obtain proper focus.Prism stool 87 which is adjustably mounted in prism housing 86 holdscoincidence prism 88 which brings the images produced by objectives 76and 39 together and in coincidence. Coincidence prism 83 consists ofprism 89 providing total internal reflection and prism 90 which reflectsthe image from objective 80. To effect this a semi-reflecting film 91 isprovided at the interface between prisms 89 and 90. As shown in FIG- URE7, prisms 89 and 90 are held in place on prism stool 87 by hold-downplate 91 which is connected to stool 87 by means of threaded fasteners92. Resilient cushions 92' are used to prevent cracking of the prisms byplate 91.

With objectives 76 and 8t) and coincidence prism 88 in adjustment theimages of lineal targets 22 on the forward and rear target stations arereflected as a coincident image which is viewed through a conventionalviewing objective 93. Mounting flange 94 secured to the wall of prismhousing 86 holds field lens 95 on which is provided a lineal reticlewhich permits the relative viewing of the reflected coincident images ofboth lineal targets 22. Objective 93 is also supported by flange 94. Thereticle side of lens 95 is covered by cover plate 96. The lens componentis held in place in internally flanged ring 97 by locking ring 98.Viewing objective 93 employs a conventional lens system with an erectinglens system and an adjustable eye piece 98. To improve the appearance ofthe sighting device, tubular shrouds 99 and 100 are used to coverobjectives 76 and 80. Shrouds 99 and 100 are enclosed by windows 101 and102 and optionally fitted with weather shields 103 and 104. Preferablyall optical components are coated with an antirefleetion coating.Eyepiece 98 is also provided with a mask (not shown) to block the visionof the unused eye of the observer.

It will be noted that each objective 76 and S0 cooperates with theviewing objective to form a telescope. The magnifying capacities of thetelescope including objective 76 and the telescope including objective8% are determined by the relative position of the intermediateobservation station from the forward and rear target stations, the ratioof the magnifying powers being equal to the ratio of the target stationdistances. For example, with the intermediate observation stationpositioned 25 feet from the rear target station and 100 feet from theforward target station the ratio of the magnifying power of the rearobjective to the magnifying power of the forward objective equals 1:4.In the illustrative embodiment viewing objective and the rear objectiveis 3X power telescope and viewing objective and the forward objectiveprovides a 12X power telescope. Other magnifying powers can be used toprovide the desired ratio. By using the magnifying power ratio systemthe images of the targets of equal length also have the same length.

In employing the subject invention as an aid in resurfacing trackstructures by raising the track, viewing device 75 is mounted onintermediate observation station 39 which is coupled to jack tie tamperon power unit 10. At the field location where a predetermined raise inthe track structure is to be made, forward and rear target stations 13and 15 are coupled to power unit 10 and the assembly moved onto leveltrack. To minimize irregularities in track structure the observationstation is preferably located closer to the rear target station. Forexample, in the illustrative embodiment the observation station isplaced 25 feet from the rear target station and 100 feet from theforward target station. It is preferred that the spacing of the forwardand rear target stations be located about 75200 feet apart and theintermediate observation station be located closer to the rear targetstation at about /a%; the total distance. Other locations and spacings,however, can be used as desired. Suitable coupling devices are employedto maintain the proper distances.

Lineal targets 22 on target stations 13 and 15 are initially placed atthe same height above the level rail structure, the height beingdetermined by the height of the optical plane of the viewing device 75.The targets are brought into horizontal adjustment and viewing de- 5.vice 75 adjusted until the target images are coincident and in alignmentwith the reticle. :In this condition the theoretical datum plane formedby the opposed targets is parallel and coincident with the optical planeof the viewing device. The forward lineal target is then raised anadditional distance equal to the predetermined amount that the railstructure is to be raised. This will vary in raising the track structureto raise the gradual run-oil section of track but will be constantduring the remainder of the track surfacing operation. The assembly ismoved onto the track to be resurfaced. It may be necessary at this timeto readjust the optical plane to maintain its proper alignment with thedatum plane. The operator locates the jack tie tamper over the selectedjack tie. In looking through the eyepiece of the sighting device it willbe observed that the coincident target images and the lineal reticle aredisplaced as is shown in FIGURE 6A. The apparent distance between theimage and the reticle line will be indicative of the amount the tracklevel will be raised. The operator, by observing the targets through theeyepiece, manipulates the jack tie tamper controls to raise the track tothe desired level. The track in being raised also raises theintermediate observation station and at the desired level the coincidentimages and the reticle will be aligned ino the viewing scope as shown inFIG- URE 6B. The machine then tamps the ballast around the jack tie tohold the raise. Raising continues with no further adjustments in thesighting apparatus.

The raise can be made by simultaneously elevating both tracks or bysequentially raising the grade track and then raising the other track.Cross level of the track can be observed in the sighting device bynoting the position of the reflected target images. If the tracks arenot cross-leveled the optical plane will be askew and the images willcross as seen in FIGURE 6C rather than coinciding. If crossing of theimages occurs the level of the other track must be adjusted to bring theimages into coincidence. In cross levelling it may also be desirable touse a spirit level, inclinometer, or the like.

Although in the foregoing description the use of the instant inventionin track surfacing was discussed in re lation to the raising of tangenttrack, it is to be understood that this invention has application inraising curved track as well as the aligning of tangent and curvedtrack. It is also apparent that various modifications can be made in theillustrative embodiments without departing from the scope of the instantinvention. The sighting device can be constructed employing otherobjective systems and by using alternative reflecting coincidence meanssuch as mirrors, semi-reflecting pellicles, and alternative prism-s forbringing the target images together and into coincidence. For example inFIGURES 14-17 several schematic optical arrangements are illustratedwhich permit the simultaneous viewing of a pair of opposed targets,positioned each to the other at an angle of 180 in coincidence andrelative to a reticle, through an orthogonal viewing objective. InFIGURE 14 no objective is used in combination with viewing objective 110which comprises spaced positive lens 111 and 112 with reticle 113positioned intermediate thereto. Reflecting coincidence prism -114employing the same prism system as used in the above described completespecific embodiment comprises a large 45 -9045 prism 115 having itshypotenuse face normal to the line of sight or optical axis directedtoward the rear target 22B. The light from target 22B is reflected froma leg face of prism 115 along an axis parallel to the hypotenuse face.The light from the forward target 22A is directed along an axis normalto the leg face of small 45 9045 prism 116, refiectedfrom the interfaceformed at the abutment of the hypotenuse face of small prism 116 and theleg face of large prism 115 and brought into coincidence with thereflected light from the rear target 2213. The coincident images formedare viewed along the axis of viewing objective 110 relative to reticle113. Sighting objective 117 is a Galilean type telescope having anafocal lens system comprising negative lens 118 and positive lens 119.In this arrangement the viewing objective is used without anaccompanying lens system to view the rear target image and itsmagnifying power is unchanged. The afocal sighting lens system 117 has amagnifying power which cooperates with the viewing lens system toprovide a telescope of appropriate magnifying power. A typicalarrangement of this type for use in a spacing of the observation station25 feet from the rear target and feet from the forward target wouldemploy a 3 X power viewing system in combination with a 4X powersighting lens system 117. For this same spacing arrangement using thedual afocal sighting lens systems shown in FIG- URE 15 the sighting lenssystem "120 which is directed toward the rearward target 2213 could havea /2 X magnifying power and the sighting lens system directed to wardthe forward target could have a 2X magnifying power. These lens systemsin combination with a 6X magnifying power viewing lens system 122 wouldprovide properly ratioed telescopic systems for simultaneously viewingthe opposed target together and in coincidence. FIGURES 16 and 17illustrate arrangements in which the optics of the sighting lens systemsare based on the relationships of the focal length of each sightingsystem to the distances of the observation station from each targetstation. In FIGURE 16 an alternative reflecting coincidence prism 125 isused. The sighting lens systems 126 and 127 are both positioned on thesame side of prism 125 and the image of the rear target 22B reflectedinto the coincidence prism 125 by means of a system of mirrors 128 and128 The reflected coincident images are viewed through a conventionalviewing system 129 with an erecting eyepiece in relation to reticle 130.For use in the above exemplary target spacing, tar-get sighting lens 126would have a focal length of s and target sighting lens 127 would have afocal length of Ks where The magnifying power of the viewing lens wouldbe selected to permit the targets to be viewed with facility. FIGURE 17illustrates another arrangement utilizing the sighting lens systems 131and 132 positioned on the same side of coincidence prism 133. In thisinstance, each of the target images 22A and 22B are reflected throughthe viewing lens 131 having a focal length of Kr and 132 having a focallength of s by means of mirrors 134 and 135 respectively. The reflectedimages are brought together and coincided by prism 133 and the reflectedcoincident images viewed in relation to reticle 136 by viewing lenssystem 137. In both the embodiments shown in FIGURES 16 and 17 the opticsystems formed by the viewing lens system and the forward targetsighting lens system and the rear target sighting lens system,respectively, have a ratio of magnifying powers which is equal to theratio of the forward and rear target distances, respectively, from theobservation station. Other optical systems can also be used wherein themagnifying powers are not ratioed. These systems are not preferredbecause they employ less sensitive expedients for determining thevarious alignments involved in using the instant invention due to eachof target image coincidence where the optical and datum planes areparallel but not aligned. Although the axes of the illustrative opticalsystem are coplanar and lie in the optical plane of the sighting device,prism and lens arrangments can be used to provide non-planararrangements as well as viewing systems having axes which are notperpendicular to the axes of the sighting systems. In all instances,however, the optical plane of the instrument will be the plane in whichthe conjugate images formed of the reticle in the viewing system by thefirst and second sighting systems positioned respectively between saidreticle and the opposed targets lie. Generally this plane issubstantially parallel to the datum plane formed by said opposedtargets. Various arrangements can also be utilized in constructing thetarget stations and observation station for use with and for coupling todifferent types of jack tie tampers. In this regard it may be desirableto provide self-propelled target stations or use mechanical arrangementscontrollable at the power unit for raising, lowering, or otherwiseadjusting the target levels or the like. Vertical incrementalmensuration indicia to provide a means for effecting raises of differentheights and for use in making run-offs after the last ful raise is madecan also be provided on the target back board. Illuminated targets canalso be used for night operations. Target back boards can be made invarious forms to minimize wind loads. Reticle design can includeilluminated reticles for night operations.

Accordingly, it is intended that the instant invention be limited onlyas set forth in the appended claims.

What is claimed is:

l. A system for facilitating the realignment of a railroad trackinstallation which comprises a forward target station and a rear targetstation adapted to be positioned on said track installation in spacedrelation, each of said target stations having a lineal target normal tosaid track installation, the lineal targets cooperating to provide adatum plane substantially parallel to an aligned grade rail; anobservation station intermediate said target stations and closer to saidrear target station and means for coupling said forward target station,observation station and rear target station a fixed distance apart toeach other, said observation station including a telescopic sightingdevice comprising a first optical system sighting along an axis on saidforward target, a second optical system sighting along an axis on saidrear target, the sighting axes of said optical systems beingsubstantially 180 apart in substantial alignment and lying in an opticalplane, a reflecting coincidence means cooperating with said opticalsystems to bring the images of said lineal targets together andcoincident to provide a target image, and an optical viewing systemhaving a lineal reticle positioned therein in alignment with saidoptical plane, said optical plane being the plane in which the conjugateimages formed of said reticle by the first and second optical systemspositioned respectively between said reticle and said targets lie, ameans adapted to directly interconnect said sighting device and saidtrack installation, and a cradle installed on said means and holdingsaid sighting device, said cradle having adjustable means cooperatingtherewith for bringing said optical plane into parallel alignment withsaid datum plane, said optical viewing system cooperating respectivelywith said first and second sighting systems to provide a first telescopeand a second telescope, the ratio of the magnifying power of said firsttelescope to the magnifying power of said second telescope beingsubstantially equal to the ratio of the distances of said sightingdevice from the forward and rear target stations respectively.

2. A system in accordance with claim 1 in which said coincidence meanscomprises a large and a small prism component having 459045 isoscelestriangular ends, the axis of said first objective being normal to thehypotenuse face of said large prism, said large prism reflecting from aleg face and providing total internal reflection parallel to thehypotenuse face thereof to the interface formed between a leg face ofsaid large prism and the hypotenuse face of said small prism, saidinterface having a multiple layer coating such that the reflection oflight from said interface and the transmission of light through saidinterface is substantially equal, the 'axis of said second objectivebeing normal to a leg face of said smaller prism, light from said secondobjective being reflected from said interface and combining with lightreflected from said first objective wherein the axis of the viewingsystem is orthogonal to the sighting axes.

3. A system in accordance with claim 1 in which said means adapted todirectly interconnect said sighting device and said track installationincludes a frame having mounted thereon track engaging wheels, anupright stanchion mounted on said frame superposed in relationship tosaid aligned grade rail, said cradle being installed on said stanchionholding said sighting device.

4. A system in accordance with claim 1 in which said observation stationis provided with an automotive power unit.

5. A system for facilitating the realignment of a railroad trackinstallation which comprises a forward target station and a rear targetstation adapted to be positioned on said track installation in spacedrelation, each of said target stations having a lineal target normal tosaid track installation, the lineal targets cooperating to provide adatum plane substantially parallel to an aligned grade rail; anobservation station intermediate said target stations and closer to saidrear target station and means for coupling said forward target station,observation station and rear target station a fixed distance apart toeach other, said observation station including a telescopic sightingdevice comprising a first objective directed toward said forward targetstation, an opposed, contrarily directed second objective directedtoward said rear target station, the sighting axes of said objectivesbeing substantially apart in substantial alignment and lying in anoptical plane, a reflecting coincidence means positioned intermediatesaid objectives and aligned with the optical axes thereof to bring theimages of said lineal targets together and coincident to provide atarget image, said coincidence means comprising a large and a smallprism component, having 459045 isosceles triangular ends, the axis ofsaid first objective being normal to the hypotenuse face of said largeprism, said large prism reflecting from a leg face and providing totalinternal reflection parallel to the hypotenuse face thereof to theinterface formed between a leg face of said large prism and thehypotenuse face of said small prism, said interface having a multiplelayer coating such that the reflection of light from said interface andthe transmission of light through said interface is substantially equal,the axis of said second objective being normal to a leg face of saidsmaller prism, light from said second objective being reflected fromsaid interface and combining with light reflected from said firstobjective, and an orthogonal viewing objective having a lineal reticlepositioned therein in alignment with said optical plane, said opticalplane being the plane in which the conjugate images formed of saidreticle by the first and second objectives positioned respectivelybetween said reticle and said target lie, and an upright stanchionadapted to directly interconnect said sighting device and said trackinstallation, a cradle installed on said stanchion and holding saidsighting device, said cradle having adjustable means cooperatingtherewith for bringing said optical plane into parallel alignment withsaid datum plane, and an automotive power unit for said observationstation, said target stations being coupled to said power unit, saidviewing objective cooperating respectively with said first and secondobjectives to provide a first telescope and a second telescope, theratio of the magnifying power of said first teelscope to the magnifyingpower of the said second telescope being equal to the ratio of thedistances of said sighting device from the forward and rear targetstations respectively.

6. For use in a track maintenance system for facilitating therealignment of a railroad track installation comprising a forward targetstation, a rear target station adapted to be positioned on a trackinstallation in spaced relation, each of said target stations having alineal target normal to said track installation and an observationstation intermediate said target stations and closer to said rear targetstation, said forward target station, observation station and reartarget station being adapted to be coupled together a fixed distanceapart each to the other, an optical viewing system adapted to be mountedon said observation station, comprising a first objective adapted tosight along an axis on one target comprising a positive lens and anegative lens spaced apart, a contrarily directed second objectiveadapted to sight along an axis on the other target comprising a pair ofspaced positive lens, a reflecting coincidence means comprising a largeand a small prism component, having 45 9045 isosceles triangular ends,the axis of said first objective being normal to the hypotenuse face ofsaid large prism, said large prism reflecting from a leg face andproviding total internal reflection parallel to the hypotenuse facethereof to the interface formed between a leg face of said large prismand the hypotenuse face of said small prism, said interface having amultiple layer coating such that the reflection of light from saidinterface and the transmission of light through said interface issubstantially equal, the axis of said second objective being normal to aleg face of said smaller prism, light from said second objective beingreflected from said interface and combining with light reflected fromsaid first objective, said coincidence means positioned intermediatesaid objectives and aligned with the optical axes thereof to bring theimages of the targets viewed by each of said objectives together and incoincidence, and an orthogonal viewing scope having an optical axisnormal to the axes of said objectives, the axes of said objectives andsaid viewing scope being coplanar and being in an optical plane, saidviewing scope being provided with a lineal reticle, said optical planebeing the plane in which the conjugate images formed of said reticle bythe first and second objectives positioned respectively between saidreticle and said target lie, said viewing objective cooperatingrespectively with said first and second sighting objectives to provide afirst and a second telescope, the ratio of the magnifying powers of thefirst and second telescope-s being substantially equal to the ratio ofthe distances from said observer to the opposed lineal targets.

References Cited in the file of this patent UNITED STATES PATENTS897,045 Young Aug. 25, 1908 2,763,932 McMillan Sept. 25, 1956 2,945,416Fuketa et al July 19, 1960 2,974,607 Talboys Mar. 14, 1961 FOREIGNPATENTS 416,182 France Dec. 2, 1909 612,775 Germany May 9, 1935 580,043Great Britain Aug. 26, 1946 269,544 Italy Nov. 22, 1929 OTHER REFERENCESJenkins and White, Fundamentals of Optics, published in 1950 byMcGraw-Hill, page 168.

1. A SYSTEM FOR FACILITATING THE REALIGNMENT OF A RAILROAD TRUCKINSTALLATION WHICH COMPRISES A FORWARD TARGET STATION AND A REAR TARGETSTATION ADAPTED TO BE POSITIONED ON SAID TRACK INSTALLATION IN SPACEDRELATION, EACH OF SAID TARGET STATIONS HAVING A LINEAL TARGET NORMAL TOSAID TRACK INSTALLATION, THE LINEAL TARGETS COOPERATING TO PROVIDE ADATUM PLANE SUBSTANTIALLY PARALLEL TO AN ALIGNED GRADE RAIL; ANOBSERVATION STATION INTERMEDIATE SAID TARGET STATIONS AND CLOSER TO REARTARGET STATION AND MEANS FOR COUPLING SAID FORWARD TARGET STATION,OBSERVATION STATION AND REAR TARGET STATION A FIXED DISTANCE APART TOEACH OTHER, SAID OBSERVATION STATION INCLUDING A TELESCOPIC SIGHTINGDEVICE COMPRISING A FIRST OPTICAL SYSTEM SIGHTING ALONG AN AXIS ON SAIDFORWARD TARGET, A SECOND OPTICAL SYSTEM SIGHTING ALONG AN AXIS ON SAIDREAR TARGET, THE SIGHTING AXES OF SAID OPTICAL SYSTEMS BEINGSUBSTANTIALLY 180* APART IN SUBSTANTIAL ALIGNMENT AND LYING IN ANOPTICAL PLANE, A REFLECTING COINCIDENCE MEANS COOPERATING WITH SAIDOPITCAL SYSTEMS TO BRING THE IMAGES OF SAID LINEAL TARGETS TOGETHER ANDCOINCIDENT TO PROVIDE A TARGET IMAGE, AND AN OPTICAL